1. Field
This relates to a dryer, and in particular, to a heat pump type dryer having multiple operation modes and an operation method thereof.
2. Background
In a laundry treating apparatus having a drying function such as a washer or dryer, once washing and dehydration are completed, hot air may be supplied into the drum to evaporate moisture from the laundry, thereby drying the laundry. Such a dryer may include a drum rotatably provided within a cabinet, a drive motor to drive the drum, a blower fan to blow air into the drum, and a heating device to heat air conveyed into the drum. The heating device may use, for example, high-temperature electric resistance heat generated using electric resistance, or combustion heat generated by combusting gas.
Here, the dryer may be classified according to a method for processing the high temperature and humid air, and thus divided into a condensation (circulation) type dryer for condensing moisture contained in the high temperature and humid air by cooling the air below the dew point temperature through a condenser while being circulated without discharging the high temperature and humid air out of the dryer, and an exhaustion type dryer for directly discharging the high temperature and humid air having passed through the drum to the outside.
In case of the condensation type dryer, in order to condense air discharged from the drum, the process of cooling the air below the dew point temperature should be carried out to heat the air through the heating means prior to being supplied to the drum again. Here, the loss of heat energy contained in the air is generated while being cooled down during the condensation process, and an additional heater or the like is required to heat the air to a temperature required for drying.
Even in case of the exhaustion type dryer, it is required to discharge high temperature and humid air to the outside and receive outside air at normal temperature, thereby heating the air up to a required temperature level through the heating means. In particular, thermal energy transferred by the heating means is contained in high temperature air being discharged to the outside but it is discharged and wasted to the outside, thereby reducing the thermal efficiency.
Accordingly, in recent years, clothes treating apparatuses for collecting energy required to generate hot air and energy being discharged to the outside without being used have been introduced to increase energy efficiency, and a clothes treating apparatus having a heat pump system has been introduced as an example of the clothes treating apparatus. The heat pump system may include two heat exchangers, a compressor and an expansion apparatus, and energy contained in the discharged hot air is reused in heating up air being supplied to the drum, thereby increasing energy efficiency.
Specifically, in the heat pump system, an evaporator is provided at the exhaust side, and a condenser at an inlet side of the drum, and thus thermal energy is transferred to refrigerant through the evaporator and then thermal energy contained in the refrigerant is transferred to air brought into the drum, thereby generating hot air using waste energy. Here, a heater for reheating air that has been heated up while passing through the evaporator may be additionally provided therein.
When the dryer is operated according to multiple operation modes in the heat pump type clothes dryer, a user may selectively enter into a first operation mode (speed mode) or a second operation mode (eco mode).
Typically, the heater is turned on to enhance the drying performance in case of the first operation mode, and the heater is turned off to save energy in case of the second operation mode.
However, in the multiple operation modes, the same flow rate of refrigerant is circulated during the refrigerant circulation cycle in both the first operation mode and the eco mode, thereby causing a problem that a required flow rate of refrigerant cannot be controlled.